The grades on a geometry midterm at Gardner Bullis are normally distributed with $\mu = 66$ and $\sigma = 5.5$. Christopher earned a $76$ on the exam. Find the z-score for Christopher's exam grade. Round to two decimal places.
A z-score is defined as the number of standard deviations a specific point is away from the mean We can calculate the z-score for Christopher's exam grade by subtracting the mean $(\mu)$ from his grade and then dividing by the standard deviation $(\sigma)$ $ { z = \dfrac{x - {\mu}}{{\sigma}}} $ $ { z = \dfrac{76 - {66}}{{5.5}}} $ ${ z \approx 1.82}$ The z-score is $1.82$. In other words, Christopher's score was $1.82$ standard deviations above the mean.